2018 - Volume #42, Issue #4, Page #28[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
“Geared-Up” Pto-Driven Generator
“I use a 38 hp. diesel engine and a 540 rpm pto to operate it. The belt-driven unit lets me run the tractor engine at only about two thirds wide open. I’m operating the pto shaft at a slower speed than the generator requires, but this unit boosts the rpm’s,” says Kohl.
“I finished building it last summer. I could have bought a commercial gas engine-powered generator, but it would have sat in my garage until I needed it. And I would have had to pull it out a couple times a year to keep it in operating condition. I can park my pto-driven generator in my garage for years until I need it.”
The generator “cage” measures 30 in. wide, 36 in. long and 28 in. high and mounts on 4 caster wheels. Kohl bought a 13,000-watt, pto-driven North Star generator at a sale for $550. He used big bearings to mount the pto shaft in place and ran a long 1 1/4-in. dia. shaft to a big pulley on back. The pulley belt-drives 3 other pulleys that drive a jackshaft that hooks up to the generator.
It needed 3,600 rpm’s in order to produce 120/240 Vac at 60 Hz. “Since a power unit needs 2 hp. per 1,000-watt generator, I needed a tractor with at least 26 hp.,” says Kohl.
“All commercial pto-driven generators need the pto to run at 540 rpm’s, which means I would have to run my tractor’s engine at 2,600 rpm’s - almost full throttle - in order to produce a pto speed of 540 rpm’s. I didn’t want my tractor to run at full throttle for a long time, so I selected a tractor speed of 1,800 rpm’s as a goal for my generator. This would run my pto at 373.8 rpm’s.
“To gear up the generator, I used some old pulleys I collected over the years. I had to do some math to figure out what I needed.
“I spent a total of less than $1,000. I paid $100 for the pto shaft, $86 for the V-belts, and $60 for the caster wheels. It took me a long time to find all the parts that I needed. I got the angle iron, shafts and bearings free where I work.”
Contact: FARM SHOW Followup, Jeff Kohl, 5259 130th Street East, Northfield, Minn. 55057 (ph 507 664-9439; email@example.com).
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